Do you make a spare negative?

When I started with LF many people told me to always make a spare negative to allow for dust, darkroom errors, etc. And this is what I've done ever since. But lately I've been wondering whether this makes sense for me. I rarely need to use a "B" negative, and as a result have boxes and boxes of them undeveloped. So I'm almost doubling my film costs to manage the risk of an occasional error. This doesn't make sense to me, hence my question here: do you make a spare negative?

Extremely rarely. As I mainly shoot LF landscapes and usually have to do a lot of walking with a backpack it's just not feasible. On the very odd occasion where lighting is extreme and I know I have sufficient film then I might shoot a second for processing separately.

I always shot both sides of the film holder with the same scene. I then developed and contact printed side A, and if it looked like a keeper, but the negative needed developing adjustment, I could do so with side B. I always kept both sides permanently in case of damage to one of them.

An interesting side note, you may recall reading Ansel Adam's commentary on the shooting of Moonrise, where he stated that he quickly made the first exposure without a meter, just guessing at the exposure, then turned the holder over intending to get a backup negative, but just then the light disappeared from the gravestones.

I used to do it, but don't anymore. Reason: cost. I am on a VERY small budget with photography. When I started using sheet film, I found a bunch of cheap expired film online, and did the double exposure. Now that I'm buying fresh film, I simply can't afford to shoot the second one. Every dollar counts.
With that said, if I was ever commissioned to shoot something, I would do back-ups without a doubt.
- Thomas

"Often moments come looking for us". - Robert Frank

"Make good art!" - Neil Gaiman

"...the heart and mind are the true lens of the camera". - Yousuf Karsh

Usually not, because it would mean having to carry twice as much film or to make half as many photographs, and it's rarely necessary. If I do it's usually because I'm thinking of printing it two different ways, and might need a denser neg for one process, or if there are some random factors that I can't control like wind, or occasionally if it's a shot that I'm fairly sure will be an interesting image, and I want to be really sure I've got it.

This thread certainly brings back memories. Since most of my shooting was on a 2 week vacation trip by van, I ended up building a case that held 100 film holders in groups of 5. All were numbered. I loaded all of them for a trip. Rarely got past using about 60 or 70 even on the longest trip, but that meant 60 or 70 individual shots with both sides exposed the same.

When leaving the van, it was easy to grab a bundle of 5 or 10 to take with me.

I never wanted to be bothered loading on the road, and it seemed a sure way to get dust on the film.

I suspect today, I'd be using ReadyPacs, though I have never seen one.

For a very short time when I first started using 4x5 I would bracket my exposures. As I only have six film holders that meant using up my negatives too fast, then having my arms buried in a changing bag while being eaten alive by mosquitoes, which sucked!

At the bottom end of the learning curve I had quite a few failures due to not metering properly, or not choosing the right exposure/development combination, or dust, or lint, or.....but those became less frequent as the years rolled by.

John Sexton shoots 2 and processes them separately - adjusting the second processing as needed for optimum quality. Since adopting this technique, I find that the fine-tuned second negative is often the "keeper".